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The diversity and ecological impact of amoebae grazing on the bloom-forming cyanobacterium Microcystis

Boek - Dissertatie

Cultural eutrophication has caused the deterioration of many shallow standing waters all over the world. Especially cyanobacteria, notorious for their toxins, proliferate at elevated nutrient concentrations thus hampering the amenities provided by the affected waters. To halt and reduce cyanobacterial bloom formation, a good ecological knowledge on the natural dynamics of these blooms is indispensable. Top-down effects (e.g. zooplankton grazing) are traditionally believed to be of minor influence due to the unpalatability of many cyanobacteria. There is however increasing evidence that specific micro-organisms are able to thrive on cyanobacterial food, seemingly less hampered by size and biochemical constrains.The work presented in this dissertation shows the importance of highly specialized grazing amoebae for the dynamics of natural Microcystis blooms, highlighting the ecological significance of microbial antagonists for cyanobacterial bloom dynamics. Their activities can at times be a major loss factor for Microcystis blooms but long-term effects on bloom biomass may be prevented by the high functional and genetic diversity of natural Microcystis blooms, allowing rapid microevolution to defended genotypes, which may be key to its ecological success.
Pagina's: 226 + annexes p.
Jaar van publicatie:2015